1. Field of the Invention
The invention relates generally to monitoring a cable, such as an overhead power line or a transmission or distribution line. More specifically, the invention is directed to monitoring the position of a cable relative to a fixed reference point or a change in such position.
2. Description of Related Art
Transmission and distribution lines, overhead conductors, or overhead power lines that are used to transmit electrical power are designed to be within governmental codes requiring certain physical clearances from the ground and other objects. For example, transmission lines must be a certain height above the ground to ensure safe operation. In the design of a transmission line factors such as tension of the line, ambient weather conditions, and anticipated electrical loads are used to insure compliance with the clearances dictated by code. Since most transmission lines are not regularly monitored, the design of these lines typically includes conservative assumptions. For example, the design capacity or electrical load of the line will be lower than the line could actually handle. As a result of these conservative designs, transmission lines typically have additional capacity that is not utilized. Further, the capacity of the line changes with weather conditions, which obviously vary over time.
This additional capacity in existing lines could be utilized, and new transmission lines would be less conservatively designed, if the physical location of the transmission line were regularly monitored to compliance with code clearances during operation. By monitoring the transmission line, its horizontal displacement and vertical displacement or sag from an initial position, can be known. In addition, other aspects regarding the physical condition of the transmission line can be observed, such as ice build-up on the line. Further still, known relationships between the sag of a transmission line or conductor and its operating temperature could be utilized to track or predict the life expectancy of the transmission line or conductor.
Based on the foregoing, there is a need for a device that monitors the physical location and condition of a transmission line that is able to report such information to a remote location as frequently as desired.